An F-15E Strike Eagle drops a GBU-28. Service officials and analysts debate whether precision weapons can replace close-air support platforms such as the A-10. (Air Force)

WASHINGTON — With budgets slashed due to sequestration, the US Air Force is eyeing vertical cuts — the removal from service of single-mission aircraft to save money that can be invested toward readiness and modernization.

One target is the A-10, a decades-old plane designed for close-air support (CAS) missions. But supporters of the plane have rallied against the service, and Congress inserted language into last month’s National Defense Authorization Act prohibiting the Air Force from cutting the platform.

While the fate of the A-10 is unclear, the battle has created discussion about the future of CAS and how best to perform the mission. Proponents of using other platforms for CAS point to precision weaponry.

“Precision-guided munitions have changed the way we have traditionally thought about CAS,” said Mark Gunzinger, an analyst with the Center for Strategic and Budgetary Assessments who served in a number of Pentagon roles. “Increasingly, what really matters is the munitions and other weapons systems that can be carried by an aircraft, not the platform itself.”

Gunzinger noted that sensors, data links and targeting pods have as much of an impact as weapons like the GBU-38 used for CAS missions on the B-1 bomber.

“So you can see why it would make sense in the future to emphasize designing weapons packages for multimission aircraft, rather than developing platforms specialized for single missions,” he said.

Those multimission aircraft include the B-1 and F-15E. Pilots who have flown those planes into CAS situations argue that, with the technology now available, including precision weapons, dedicated close-air support platforms are no longer needed.

“The A-10 was designed for when you need to do visual map-to-ground, and that’s not our primary, or preferred, way of delivering CAS anymore,” said one B-1 pilot with extensive CAS experience.

“It’s about communication, command and precision,” added an F-15E pilot who has flown numerous CAS missions. “With helmet-mounted data, you can cue up targets, see much more than you were able to before. You always know where the target is.

The disagreements over precision weapons run parallel to the arguments around the continued use of the A-10.

Proponents of the A-10 claim precision munitions pose a danger to friendly forces on the ground. A 2009 Pentagon document defines the “danger close” range for forces standing on the ground — the range at which there is an increased chance of friendly fire — as 200 meters for a GBU-39 small diameter bomb.

In comparison, the “danger close” range for the A-10’s gun is listed at 90 meters.

The newest version of the small diameter bomb — the SDB-II — could help with issue, Gunzinger said.

“It’s a smaller weapon and can create effects with more precision and lower probability of unintended damage to close-in troops,” he said. “I think that is going to be a very valuable weapon in the future.”

But the service will likely never move away from the gun entirely.

“I’ve switched up attack runs that were supposed to be bombs to use the gun because it was too close to our troops or civilian structures,” the F-15E pilot said. “I don’t think you can build a bomb small enough to match the gun.”

One veteran A-10 pilot argued that the time between launch and impact of precision weapons can be taken advantage of by enemies on the ground.

“I’ve watched guys drop GBUs from medium altitude on a group of bad guys, only to have the group split up or move, and the GBU, with a long time of fall, miss the target completely,” the pilot said. “Smart enemies move.”

That lag time diminishes the closer the plane is to the ground, but just how low an F-15, B-1 or, in the future, F-35, would go during a firefight could limit use of the weaponry. He also points out that high-tech weaponry is reliant on data links that could fail at a critical time for American forces on the ground.